28 PHYSIOLOGY FOE THE LABORATORY. 



G. The Work of Muscles and Bones. Levers. 



Apparatus. A wooden rod about a yard long. Weights of dif- 

 ferent sizes. A triangular prism of wood for a fulcrum. A spring- 

 balance. 



Arrange the different parts to show the kinds of levers. 

 One weight will represent the " weight," and the spring- 

 balance will measure the power. Change the weight and 

 notice the effect on the power. The power arm is the 

 distance from the power to the fulcrum, and the weight 

 arm is the distance from the weight to 'the fulcrum. Find 

 the relation of the product of the power and the power 

 arm to the product of the weight and the weight arm. 



Show the three kinds of levers : 



a. When the fulcrum is between the power and the 

 weight. 



b. When the weight is between the power and the ful- 

 crum. 



c. When the power is between the weight and the ful- 

 crum. 



H. The Lever in the Arm. 



NOTE. These problems maybe solved arithmetically or worked 

 out on Dr. Fitz's lever apparatus. 



1. The bones of the forearm act as a lever. Part of the 

 power is the biceps muscle attached on the inside 

 just below the elbow. 



a. Where is the weight? the fulcrum? 



b. What is the length of the power arm ? of the weight 

 arm? 



G. Which kind of lever is this ? 



